Formative Assessments are more central to individual learning during instructional phase than comparing achievements of students after instructional phase is over. As such grading students during formative assessments can be counterproductive

But this should not inhibit from allocating marks to questions in formative assessments as they are yardsticks to measure individual performance and not for comparison. Further today technology provides for self assessments to be so much individual that peer comparison can be avoided.

Marking makes it easier for technology to monitor progress over a period of time as compared to just subjective remarks.

However more important than marking is to effectively use assessment feedback to be used as guidance for improvements.